Firearm gas blocks channel a portion of the pressurized gas behind a fired bullet, redirecting it up and back along the barrel through an associated gas tube. Pressurized gas coming from the gas tube causes a bolt carrier to expel the used bullet casing, cock the hammer and load the next bullet for firing. High pressure ammunition, oversized gas ports, and silencers can cause excessive recoil, particularly in AR15/M16 rifle platforms.
An effective way to reduce rifle recoil is to reduce the velocity of the bolt carrier by reducing the volume of gas flowing through the gas block. Existing gas blocks have a variety of drawbacks. They must be custom ordered to fit specific barrel lengths, are difficult to adjust in the field, and have a limited number of settings (i.e., on or off). An adjustable gas block is therefore needed which fits a variety of barrel lengths, is easily adjustable in the field, and which has a large variety of pressure settings.